What kind of an object is it? A table? A view? Something else (materialized view, perhaps)? As if the current user lacks certain privileges on fetching metadata for that object ... On a second thought, I have no idea whether that's even possible - owner should see everything he owns. Maybe someone more experienced in the DBA field knows what's going on.

OK, if query you ran results in something, then USER_VIEWS is accessible to you. Which means that it might be a TOAD bug. However, as you said in a message #667306 said that "it is working for other schema's well", then it is probably not a TOAD bug.